One of the key aspects of science, including social science like sociology, is exploring whether what holds true for a single person or small group of people is also true for large groups of people. This book is an autobiography of three men. It is not a scientific exploration of the role that schools play in the outcomes of whole groups of people; that is the type of evidence Perry is reflecting on. There are different conclusions reached by different scientists; what is important is that the scientific method is used rather than memoir.